Tobacco-leaf separator



Dec. 26, 1967 w. c. HORSEY TOBACCO-LEAF SEPARATOR 2 Sheets-Sheet 1 Filed Feb. 9, 1965 ISA 7 INVENTOR, MAL/4M C floesa ATTORNEYS w. c. HORSEY TOBACCO-LEAF SEPARATOR Dec. 26, 1967 2 Sheets-Sheet 2 Filed Feb. 9, 1965 mvmon, MAL/4M C #azsa ATTORNEYS United States Patent 3,360,125 TOBACCO-LEAF SEPARATOR William C. Horsey, Towson, Md., assignor to The John B. Adt Company, Timonium, Md., a corporation of Maryland Filed Feb. 9, 1965, Ser. No. 431,338 14 Claims. (31. 209-12) ABSTRACT OF THE DISCLOSURE An arrangement wherein a mixture of particles are pneumatically classified by flowing a stream of air downwardly and projecting said mixture across said stream so that gravity and said airstream act in unison while flowing downwardly together to achieve an initial separation of the heavy particles from the light particles; thence, the stream being sharply curved through an acute angle to achieve a final separation by centrifugal force. The heavier particles are collected near the outside of the curve in a comparatively quiescent settling zone while the lighter particles are collected near the inside of said curve where maximum velocity occurs. The heavier particles are further classified by a screen in the quiescent zone and the overall velocity is increased by a tapering of the separation chamber.

This invention relates to improvements in a machine and process for classifying threshed tobacco leaves for the purpose of separating the stemless lamina from the stem-bearing lamina and stems.

It is a primary object of this invention to provide a machine and process for thus separating light from heavy particles or strips of tobacco or other material by classifying the fragments or particles in accordance with different trajectories pursued by them When projected transversely through one portion of a flowing airstream, and further classifying such particles by diverting the said airstream in a direction transverse to the initial direction of flow of the airstream, whereby to utilize the action of centrifugal force in achieving a further separating or classifying action.

Further, in accordance with the invention, it is an object to initially project the mixed material generally horizon tally across a downflowing airstream having a substantially uniform velocity throughout its cross section and then to sharply divert said downflowing airstream laterally in a direction counter to the trajectories of the respective particles of material to produce a still further separation of the already classified particles by the combined actions of gravity and centrifugal force.

It is a further object to still further facilitate the classifying action arising from centrifugal force by accelerating certain portions of the fiow of air with respect to others, in a manner to intensify the classifying effects of centrifugal force.

It is a further object to simultaneously classify the strips or particles of material according both to size and mass.

Thus, in accordance with the invention, the flowing airstream is directed downwardly at a substantially uniform velocity throughout its horizontal cross section, and the mixture of material to be separated is projected horizontally across such stream so that the heavier particles will travel to the remote side of said stream from the location of their projection, while the lighter particles will travel a lesser distance, thereby separating the heavy and light particles transversely of the airstream. The downflowing stream with its entrained particles is then diverted transversely from its initial path of movement to a direction generally counter to the trajectories of the particles at the time of their entry into the stream, whereby to ice further displace the heavier particles toward the outside of the curve thus pursued by the airstream and to cause the inner portion of said curving stream to carry away the lighter particles. At the same time, such diversion of the airstream accelerates the inner portion thereof bearing the lighter particles to a high velocity to thus better remove said lighter particles, while at the same time radially outwardly displacing any heavier particles to a portion of the airstream having a relatively lower velocity and flowing in a curved path of relatively greater radius than the lighter particles.

In the accompanying drawings:

FIGURE 1 illustrates a vertical cross section through a separating machine embodying the improvements of the present invention;

FIGURE 2 is a fragmentary enlarged perspective view of the rear portion of the separating chamber, same being taken substantially on the line 22 of FIGURE 1; and,

FIGURE 3 is an enlarged plan section of the bottom portion of the apparatus taken on the line 33 of FIG- URE 1.

Referring now in detail to the accompanying drawings, the separating chamber 10, best shown in FIGURE 1, is housed within a casing generally designated 11 having relatively laterally spaced vertical side walls 12 and 13, a back wall 14, a front wall 15, a bottom generally designated 16, and also a top wall 17.

The separation chamber 10 is provided with an air inlet opening 18, preferably containing a conventional flow straightener 20 through which the air from a suitable plenum chamber 21 is caused to enter the separating chamber 10 as a vertically downwardly moving stream of substantially uniform velocity throughout its horizontal cross section. It will be understood that air is supplied to the plenum chamber 21 from any suitable source, comprising if desired air which is recirculated by a conventional blower (not illustrated) in known manner. It suffices for the purposes of the invention that the air which is within chamber 21 be under a greater pressure than the air downstream therefrom so as to cause the desired air flow.

The discharge opening or outlet 22 for the separation chamber opens laterally through the rear of the chamber, being defined in the present embodiment by the laterally opening mouth of a primary discharge passage 22A extending between upper and lower baffles 23 and 24 respectively which are supported between the relatively opposed side walls 12 and 13 of the casing, with the discharge opening 22 at a level substantially below the intake opening 18, but above the bottom of the chamber 10.

The discharge opening 22 will be seen to be of substantially smaller cross sectional area than the intake opening 18 so as to substantially increase the velocity of the airstream as it enters the said opening. The outflowing air must make a sharp bend around and beneath the lower horizontal edge 25 of the baflie 23.

In addition to cooperating with the upper baffle 23 to define the primary air discharge passage 22A, the lower baflie 24 is in such spaced relation from the rear wall 14 of the casing as to define a secondary air discharge passage 26 which merges upwardly with the primary passage 22A at the upper ends of said passages so that same may communicate with a common discharge conduit 27 as shown in FIGURE 1. A damper plate 28 hinged to the upper horizontal edge of the baflle 24 provides means for controlling the relative rates of fiOW of air through the respective secondary and primary passages 26 and 22A, the air flow for secondary passage 26 being furnished in a manner later to be described.

Located above the discharge opening 22, and at one side of the uniformly downwardly moving airstream through the inlet opening 18, is a rotary winnower 30 which is partially housed in a cylindrical recess in the upper baffle 23 with its shaft 31 rotatably supported through the opposite side walls 12 and 13 of the casing, and rotatably driven in a counterclockwise direction, as best seen in FIGURES l and 2, by suitable means which, being of a conventional nature, is not herein .shown. The infeed opening 32 through which the tobacco or other material to be classified is delivered into the machine, is located above the winnower and the material may be delivered through this opening by conventional means, here exemplified by the outlet portion 33 of a cyclone separator having its lower end communicating with the opening 32, and having disposed therein a conventional rotary air lock 34.

It is important to note that in the preferred embodiment the winnower 30 and the discharge opening or mouth 22 are both located on the same lateral side of the separation chamber 10 between the inlet opening 18 and the bottom of said chamber, the winnower being arranged to project the tobacco or other material generally horizontally across the downflowing airstream at a level where the same is of substantially uniform velocity throughout its horizontal cross section. The outflowing air from the chamber 10 moves into the discharge opening in a direction counter to the direction in which the material is projected across the chamber by the winnower 30.

It will be understood from the above that the winnower 3t exemplifies any suitable means at one lateral side of the separation chamber 10 for projecting a mixture of heavy and light particles generally horizontally across the downflowing airstream.

The front wall 35 of the separation chamber 10 comprises one of two relatively sloping walls 35 and 35, which converge downwardly to function as a chute, the bottom of which comprises a housing 37 for an auger conveyor 38.

Disposed over the mouth of the chute defined by walls 35 and 36 is an inclined screen 40 having its mesh of appropriate size to permit passage therethrough of the comparatively heavy particles of sand and dust which may he intermingled with the tobacco and projected across the chamber 10 by the winnower 30, while barring the passage of the comparatively larger stems and other heavy matter. The heavy particles intercepted by the screen are free to move down the inclined screen 40, both under the influence of gravity and of the downwardly moving airstream, for reception on the upper and rearwardly moving run of the endless conveyor 41. In accordance with usual practice, the conveyor 41 has its discharge end located above a rotary air lock 42 but in somewhat spaced relation thereto. The air lock 42 in turn discharges such particles of material onto any conventional conveying means, as for instance a conventional belt conveyor 43 for removal to any desired point of discharge.

It is to be noted that the conveyor 41 is spaced substantially below the discharge outlet or opening 22 so as to leave below said opening and above the belt 41 a settling zone 45 in which the air velocity is low and which may therefore be regarded for practical and comparative purposes as a quiescent zone.

In accordance with known practice, the lower run of the bottom discharge conveyor 41 is spaced above the bottom 16 of the casing to therewith define an air passage 46 through which air is delivered rearwardly and upwardly through the stream of material discharged from the conveyor 41 and thence upwardly through the secondary discharge passage 26"and into the discharge conduit 27. Such air flow or stream functions in usual manner to glean from the discharged heavy material any lighter fragments that might have been intermingled or entrapped with other heavier particles on the conveyor 41, and returns these to the stream of lighter particles or fragments entrained in the air flowing through the conduit 27.

In accordance with the present invention, the flow of air through the passage 46 is supplied directly from the plenum chamber 21 through a bypass passage 46A opening into said chamber above the intake opening 20 of the separation chamber 10 and extending beneath the auger housing 37 into communication with passage 46. This auxiliary passage is defined by the relatively spaced walls 35 and 15 and the relatively spaced auger housing 37 and casing bottom section 16A.

A flexible sheet material element 48 carried by and depending from the trough wall 36 has its lower edge in snug wiping engagement with the upper run of the conveyor 41 to form an air seal for preventing the flow of air from the passages 46, 46A over the upper run of the belt conveyor 41. Thus the relative low velocity or quiescence of air in the settling zone 45 is preserved.

In the operation of the invention, the threshed tobacco leaf fragments or particles are delivered by the infeed mechanism 33 downwardly through the infeed port 32 and onto the rotary winnower 36, the vanes of which project such particles horizontally across the chamber 10 and toward the front thereof at a level Where the airstream flowing downwardly through the flow straightener 20 has a substantially constant velocity throughout its horizontal cross section.

The comparatively heavier stems and particles of sand will normally have comparatively long trajectories so that the sand and heavy dust particles will pass through the screen 4i} to be then delivered into the auger conveyor 38 for discharge, while the comparatively larger particles of stem or other matter which reach the screen 4% will be caused to slide down the face of same and onto the conveyor 41, both by the action of gravity and by the downwardly moving airstream.

The projecting of the material transversely across the downwardly flowing airstream in the foregoing manner will be seen to have transversely classified the particles of material so that the heavier particles having relatively long trajectories will be disposed near the front of the chamber 10, while the lighter particles having relatively short trajectories will remain near the rear thereof.

As the airstream approaches the level of the discharge opening 22, it will be sharply diverted in a lateral direction around and beneath the horizontal bafile edge 25 to enter the discharge opening 22 and primary discharge passage 22A. In doing so, it assumes an increased velocity, since the flow area of the mouth 22 is substantially less than that of either the inlet opening 18 or the cross section of the separation chamber 10 between the inlet and discharge openings 18 and 22.

Because of the influence of the sharp bend or curve thus produced in the airstream, the velocity of the air adjacent the outside or larger radius of the curve or bend will be substantially less than the velocity of air adjacent the smaller radius where the airstrearn flows around and beneath the lower edge 25 of the bafiie 23. This acceleration is compounded, as above mentioned, by the over-all increase in velocity that arises due to the reduction of flow area as the airstream enters the discharge opening 22.

After having been transversely classified by differences in their trajectories across the downflowing airstream, the particles are subjected to a further centrifugal separation or classifying action arising from their curved path incident to movement of the airstream at increased velocity into the discharge opening 22. The heavier particles, which will already have been largely displaced into the outer radius of this curved path, will tend to be still further outwardly displaced by centrifugal force into increasingly lower velocity portions of the curving airstream, While the relatively lighter particles of material which remain near the baffle 23 will pass around the small radius curve adjacent the haflle edge 25 to enter the high velocity portion of the airstream flowing into the discharge opening 22. The comparatively heavier particles thus displaced to the outside low velocity portion of the curved path of the airstream will move into the settling zone 45 to be received upon the discharge conveyor 41 and removed via the air lock 42 and conveyor 43. The lighter particles which may have become intermixed with heavier ones and carried onto the belt conveyor 41 will be gleaned from the heavier particles by the air current through passages 46A and 46 and carried upwardly through the secondary air passage 26 into the discharge conduit 27, there to merge with the outflowing stream of air and entrained lighter particles flowing through the primary discharge passage 22A. It will be readily apparent that as the airstream is diverted from a generally vertically downward path to a lateral direction in entering the discharge opening 22, the separating action of centrifugal force will be augmented by the action of gravity in classifying or separating the heavier particles from the light ones.

Thus from the foregoing, it will be apparent that in moving through the separation chamber 10, a mixture of comparatively heavy and light particles will be subjected to a classifying action arising from differences in their trajectories across the airstream, as well as to a mechanical sifting action by the screen 40, and in addition will be subjected to a centrifugal classification or separation augmented by the action of gravity and by the acceleration in the air flow as it enters the discharge opening 22. In addition, it is of extreme importance to note that the separating action is further enhanced by the differences in velocity across the curving airstream as it approaches thedischarge opening 22.

Having thus described my invention, I claim:

1. The process of classifying a mixture of relatively heavy and relatively light particles of matter comprising the steps of flowing a stream of air downwardly at a substantially uniform velocity throughout the horizontal crosssection of said stream, projecting said mixture horizontally in a given direction across said downwardly flowing stream so as to be acted on in unison by gravity and said airstream while flowing downwardly to produce a transverse separation of the heavier particles at maximum radii from the lighter particles at minimum radii arising from their different trajectories, sharply diverting said downwardly flowing airstream in a generally horizontal direction counter to said given direction to produce a graduated velocity curving airstream across a radial cross section thereof, said curving airstream ranging from maximum velocity at its minimum radiito minimum velocity at its maximum radii corresponding respectively to said minimum and maximum radii of the trajectories of said particles, whereby said velocities further act on said particles to enhance said transverse separation by accelerating said lighter particles and decelerating said heavier particles to achieve a final separation by centrifugal force, and collecting the classified particles at said minimum and maximum radii.

2. The process defined in claim 1 including the further step of accelerating the over-all velocity of the said airstream while thus diverting it.

3. The process defined in claim 2 including the further step of screening out the smaller from the larger heavier particles at said maximum radii in the radially outer portion of said airstream after said initial separation.

4. The process of claim 1 wherein said airstream is diverted sufficiently to cause said curving airstream to form an acute angle.

5. The process of separating heavy and light particles from a mixture of said particles comprising flowing a stream of air downwardly rectilinearly and at a generally uniform velocity throughout its cross section into a separation chamber and thence at a relatively higher velocity in a lateral direction through an outlet opening of the chamber whereby to produce a sharp curve in' the said airstream within the chamber, and a graduation of the velocity of said airstream throughout the radial cross section of said curve, projecting a mixture of said particles substantially horizontally across the rectilinearly flowing portion of said airstream in a direction parallel and opposite to said lateral direction so as to be acted on in unison by gravity and said airstream while flowing downwardly in said classification chamber whereby to achieve initial transverse classification of heavier and lighter particles across said airstream arising from their trajectories, causing said initially classified lighter particles to enter along the inside of said sharp curve in said airstream so as to be acted on by said relatively higher velocity of said airstream on said inside of said curve whereby to achieve final transverse classification by the action of centrifugal force arising therefrom to supplement said initial classification, collecting said heavy particles near the outside of said curve in the lower velocity portion of said curving airstream by settling out of the same by gravity and collecting said lighter particles near said inside of said curve.

6. A pneumatic separator comprising a hollow casing defining therein a separation chamber, means at the upper portion of said chamber for directing into said chamber a downwardly rectilinearly flowing stream of air of substantially uniform velocity throughout a horizontal cross section thereof, means at one lateral side of said chamber for projecting a mixture of particles generally horizontally in a given direction across said stream at a predetermined level above the chamber bottom so as to be acted on in unison by gravity and said airstream while flowing downwardly to achieve initial classification, means defining an air discharge passage opening laterally into said chamber from said one lateral side thereof at a level below said predetermined level but above the bottom of the chamber, for causing said airstream to pursue a sharply curved path within the chamber in spaced relation above the chamber bottom with high velocity air at the top of said curved path to achieve final classification by the action of centrifugal force arising therefrom to supplement said initial classification and with lower velocity air at the bottom of said curved path so as to leave a comparatively quiescent settling zone above said bottom, said air discharge passage serving to collect the lighter particles of said mixture, and an endless conveyor having an operative run moving laterally across the chamber in said quiescent zone toward said one lateral side thereof and defining the bottom of said chamber for removing therefrom the settled-out heavier particles.

7. The combination of claim 6 wherein said sharply curved path forms an acute angle.

8. A pneumatic separator comprising a hollow casing defining therein a separation chamber, means at the upper portion'of said chamber for directing into said chamber a downwardly rectilinearly flowing stream of air of substantially uniform velocity throughout a horizontal cross section thereof, means at one lateral side of said chamber for projecting a mixture of particles generally horizontally in a given direction across said stream at a predetermined level above the chamber bottom so as to be acted on in unison by gravity and said airstream while flowing downwardly to achieve initial classification, means defining an air discharge passage opening laterally into said chamber from said one lateral side thereof at a level below said predetermined level but above the bottom of the chamber, for causing said airstream to pursue a sharply curved path within the chamber in spaced relation above the chamber bottom with high velocity air at the top of said curved path to achieve final classification by the action of centrifugal force arising therefrom to supplement said initial classification and with lower velocity air at the bottom of said curved path to leave a comparatively quiescent settling zone above said bottom, said air discharge passage serving to collect the lighter particles of said mixture, means to collect the heavier particles from said settling zone.

9. A pneumatic separator comprising a hollow casing defining therein a separation chamber, means at the upper portion of said chamber for directing into said chamber a downwardly rectilinearly flowing stream of air of substantially uniform velocity throughout its cross section, means for projecting a mixture of particles in a given direction transversely across said stream at a predetermined level above the chamber bottom so as to be acted on in unison by gravity and said airstream while flowing downwardly to achieve initial classification, means on the same side of said chamber as said projecting means defining an air discharge passage opening from said given direction into said chamber at a level below said predetermined level but above the bottom of the chamber, for causing said airstream to pursue a sharply curved path within the chamber in spaced relation above the chamber bottom with high velocity air at the top of said curved path to achieve final classification by the action of centrifugal force arising therefrom to supplement said initial classification and with lower velocity air at the bottom of said curved path whereby to leave a comparatively quiescent settling zone above said bottom, said air discharge passage serving to collect the lighter particles of said mixture, means to collect the heavier particles from said settling zone.

10. A pneumatic tobacco separator comprising a hollow casing having therein a separation chamber, means at the upper portion of said chamber for directing into said chamber a downwardly rectilinearly flowing stream of air, means at one side of said chamber for projecting a mixture of tobacco particles in a given direction generally transversely across said stream so as to be acted on in unison by gravity and said airstream while flowing downwardly to achieve initial classification, means defining an air discharge passage opening from said chamber transversely to said rectilinearly flowing airstream for causing said airstream to pursue a sharply curved path Within the chamber with high velocity air at the top of said curved path to achieve final classification by the action of centrifugal force arising therefrom to supplement said initial classification and with lower velocity air at the bottom of said curved path, said curved path forming an acute angie to cause said stream to leave the chamber in a direction counter to said given direction, said air discharge passage serving to collect the lighter particles of said mixture including the leaves of said tobacco, and means for removing heavier particles including the stems of said tobacco and foreign matter from the radially outer portion of said curved path.

11. A pneumatic tobacco separator as defined in claim 10 in which said last-mentioned means includes a settling zone.

12. A pneumatic tobacco separator as defined in claim 10, including a screen disposed across said chamber from said means for projecting the mixture of tobacco particles, for classifying according to size any heavy particles projected thereagainst.

13. A pneumatic tobacco separator comprising a hollow casing having therein a separation chamber, means at the upper portion of said chamber for directing into said chamber a downwardly flowing stream of air of uniform velocity throughout a horizontal cross section of said stream, means at one lateral side of said chamber for projecting a mixture of tobacco particles in a given direction generally horizontally across said downwardly flowing stream at a predetermined level above the chamber bottom, so as to be acted on in unison by gravity and said airstream while flowing downwardly to achieve initial classification, means defining an air dis-charge passage opening laterally into said chamber from said one lateral side thereof at a level below said predetermined level but above the bottom of the chamber for causing said airstream to pursue a sharply curved path within the chamber and above the chamber bottom with high velocity air at the top of said curved path to achieve final classification by the action of centrifugal force arising therefrom to supplement said initial classification and with lower velocity air at the bottom of said curved path to leave a comparatively quiescent settling zone in the chamber above its bottom, said air discharge passage serving to collect the lighter particles of said mixture including the leaves of said tobacco, a vertically inclined screen defining the side of said chamber remote from said one lateral side in said settling zone for receiving the heavier particles of said mixture and for sifting out sand and dust particles from the tobacco stems, means to collect the heavier particles of said tobacco including said stems from said settling zone.

14. A pneumatic tobacco separator as defined in claim 13, wherein said air discharge passage has a smaller flow area than said chamber, to accelerate the air flowing toward and into said discharge passage.

References Cited UNITED STATES PATENTS 1,938,791 10/1933 Norman 209-143 2,051,107 8/ 1936 Rourke 209- 2,941,667 6/1960 Hilgartner 209-134 3,164,548 1/1965 Rowell 209-139 FRANK W. LUTTER, Primary Examiner. 

1. THE PROCESS OF CLASSIFYING A MIXTURE OF RELATIVELY HEAVY AND RELATIVELY LIGHT PARTICLES OF MATTER COMPRISING THE STEPS OF FLOWING A STREAM OF AIR DOWNWARDLY AT A SUBSTANTIALLY UNIFORM VELOCITY THROUGHOUT THE HORIZONTAL CROSSSECTION OF SAID STREAM, PROJECTING SAID MIXTURE HORIZONTALLY IN A GIVEN DIRECTION ACROSS SAID DOWNWARDLY FLOWING STREAM SO AS TO BE ACTED ON IN UNISON BY GRAVITY AND SAID AIRSTREAM WHILE FLOWING DOWNWARDLY TO PRODUCE A TRANSVERSE SEPARATION OF THE HEAVIER PARTICLES AT MAXIMUM RADII FROM THE LIGHTER PARTICLES AT MINIMUM RADII ARISING FROM THEIR DIFFERENT TRAJECTORIES, SHARPLY DIVERTING SAID DOWNWARDLY FLOWING AIRSTREAM IN A GENERALLY HORIZONTAL DIRECTION COUNTER TO SAID GIVEN DIRECTION TO PRODUCE A GRADUATED VELOCITY CURVING AIRSTREAM ACROSS A RADIAL CROSS SECTION THEREOF, SAID CURVING AIRSTREAM RANGING FROM MAXIMUM VELOCITY AT ITS MINIMUM RADII TO MINIMUM VELOCITY AT ITS MAXIMUM RADII CORRESPONDING RESPECTIVELY TO SAID MINIMUM AND MAXIMUM RADII OF THE TRAJECTORIES OF SAID PARTICLES, WHEREBY SAID VELOCITIES FURTHER ACT ON SAID PARTICLES TO ENHANCE SAID TRANSVERSE SEPARATION BY ACCELERATING SAID LIGHTER PARTICLES AND DECELERATING SAID HEAVIER PARTICLES TO ACHIEVE A FINAL SEPARATION BY CENTRIFUGAL FORCE, AND COLLECTING THE CLASSIFIED PARTICLES AT SAID MINIMUM AND MAXIMUM RADII. 